Bryant Gumbel’s son was charged with snatching a purse from a terrified woman on the Upper East Side early yesterday, knocking her to the ground before fleeing.

The arrest of Bradley Gumbel, 23, comes as his TV-star dad is set to tie the knot with longtime mistress Hilary Quinlan tomorrow at the posh Breakers Hotel in Palm Beach.

But Gumbel lawyer Benjamin Brafman called the arrest a “case of mistaken identity” and insisted his client – a “well-mannered young man” – would be cleared.

The Manhattan District Attorney’s Office was reviewing the case and re-interviewing witnesses last night.

Bradley Gumbel was charged with attempted robbery in the attack on a 30-year-old interior designer at about 2:10 a.m. in front of 400 E. 71st St. as the woman was heading home from a night out.

Cops say Gumbel – who stands 6-foot-5 and weighs about 250 pounds – sneaked up from behind, grabbed his victim and furiously tried to wrestle her pocketbook away.

As the woman struggled to keep her property, her attacker violently knocked her to the ground before falling on top of her like dead weight, police said.

She extricated herself and ran off without her purse, which contained $75 cash, a credit card and a Tiffany bracelet, authorities said.

The robber grabbed the purse and tore down the street in the opposite direction.

The victim rode around the neighborhood with cops, spotted Gumbel at Second Avenue and 80th Street and identified him as her attacker.

Once in custody, Bradley told police he was Bryant Gumbel’s son. A short time later, cops got a call from celebrity lawyer Johnnie Cochran asking about Bradley’s status.

Gumbel told his mother, June, he didn’t know anything about the attack. He said he had just dropped off a date and was heading to the East 72nd Street apartment he and his mom share when cops picked him up.

Cops said the woman whose purse was snatched was badly shaken and her knee injured, but she refused treatment.

Bradley’s arrest is likely to put a damper on his dad’s nuptials. Representatives for Bryant Gumbel did not return calls.